SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9171e2a59113990e3f40bb3be93dd37874cf44f5f0ada5be17d6f4113619f4f9' 
  AND token = '5J/HXaDMszLZWCgYLCHwjMd1iTPdgKlG4vAj60xs0fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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