SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f510d91d1fe948cead50c7a778764cd0dcfa182f641613552df619102bcab0c5' 
  AND token = 'zdURnnG+Lcl2Olnqh4bZwKFHiU0qb/ou/DyhfSSD0WM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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