SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d6121534e5d9a5192a3386f2c0a6f2bd96b068419314525df46fc7a64409161' 
  AND token = 'yyV8XEpmJmOnDrLWfNX6HTKBJrqesMYMRgp3r/4VM/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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