SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2ce98c4d99ffa3b5edd1a8d903aa31024cb740e1cd26d4584a36f7f7386f8e4' 
  AND token = 'pDYRQJuByu/81I+FXeRXjjxMpsLS1kGG7UBeHxDnqSQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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