SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b4d16646a38e03e2df5efabab1b8ef00e278ad513fe23473e6f870e77356ca4' 
  AND token = 'vq14Ii/Fdq2DnpKl8lAZzl9f4Z3uwEJ2vyPwM9snQGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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