SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '762626dc2132e309d80db38009fee3575ece1f7edcce307dddfa18156847b3da' 
  AND token = 'ELJjCLZaNJRI8SFbVRiQ5UCB/Beg8kZGbzj+BTKxKOQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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