SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '61f0a575c01564786102513e021b1e2f9f059368f9e5bed266cfe9a1a178cdb6' 
  AND token = 'b5MajrlscSg2o2ex4FtDjxDiqXxGW1g3LMIqWtCsnAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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