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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8f634968db07574b1a57b173b1a2fdff29e1ee4003d2b52b58faff00148e2da' 
  AND token = 'Bj6Cy5rRoGUq6CxTvkASMSA0tG9iyOwnNAmjf2B/Yhc=' 
  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"
    }
  }
}