SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '231f780ad8e6856ef5649ebd4e2504e7563fda21ec6c072c311322fe79ffe10b' 
  AND token = 'xvFnf/QykzjhWSU1qfChMn7vrynZZAAQDoCgMp5m2jI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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