SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3369e955a4f679381039e1209b346f3f1bce21b6d7c6bb8719c7a559650341c' 
  AND token = 'bq1hW01kKKiQyAGuqW3HBQEVLRqL2hqAkypaRgCu/HI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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