SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9c8e51b6ffb039fbf17e4556eb4cbd7462d49608578c12081beb14125a9a19d' 
  AND token = '9175YjjNxhXJMCEyZ3AyY+5ZFQr0rjmM3YnJo/RSiKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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