SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '604b73e6fe29d23b0c5502868d0769e610f07ef45e61bead11212dbe376a9855' 
  AND token = 'aQf5m2pxqGvrSqUm+ZhDcKOgiuLHDYLRHw3OHAbxfDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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