SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6398276580ae9a8eba97a0b4ef761620ed5c4ad56b371da24bf1ca36ebfaf6dd' 
  AND token = 'dRIXHcr95JQFTJOBLNP/DyA0mqpas6IkaPeVrBLuEVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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