SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52540a10ab79d03c20fd35cda4b90a79360c5859fd322275a3df6ee243484aeb' 
  AND token = '4c1/LtoCjtEmyAnWHoxh1bHuSAxzAfo6fk93CcqWeGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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