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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2873a87b99b917a252f447999addc5c7619f4a7e86a1f37f6eb05b91ddf165e1' 
  AND token = 'p0lqN6VhV4ds5Y1dEhGMfVNh5rBmqCMqlpyhKv6Uplk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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