SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f31ad068b9a9052d6f51b67fbc2bab909131c266d904c9aefbb2d6d51a1aa0bf' 
  AND token = 'rEqT1nUWrPRgu8iteGmeBMZE+0ymdiswzbNgb+zPFaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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