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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87b02e38e3b402a0813f1e321d854755a8737c2f5185d36a0d9fbd6683ce7ff7' 
  AND token = '1BwYjXEPP1gP9f5MJmqDE3MiiUXY8CUImiT8TR43kCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}