SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '750f3d68af9601771c5d0a01f526223cdfe2c930ba568b575a84fdbbd0a86e04' 
  AND token = '+uNlF1HclMjMZtQW9RFV6XgDETu3QzOOrHb5HIUbQqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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