SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '11d1c52196fa64c46817072a58af63ecdc98826914860b503c6b56c2edbbe91c' 
  AND token = 'qFBMCs/HfK+bT31rJfTJGpJQMydbjpeAyfKEUJtRm2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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