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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '68ce5052fde3564c22ca54d5478563cad4b13f124d42ebe7fc16e4730b42e6c3' 
  AND token = 'iooqfsd3QLuvmKhQHBeONptvlS+J3MTZaa0t3PWHsow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}