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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a64d53ba83f8e680243befcbc285d244ebf7a888e68ae5fecaa5bdd4e1c7ca81' 
  AND token = '4LL1Ep+Y2Df9tKvF5u0W63gGX4BMrLPg5GqupuzSk0E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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