SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f408435db6f5d0d1128479389eb540767a6f53740581e7974aa1487de8bae6b' 
  AND token = 'xu54EG2eEPLh7W2DqEkVIqtzTmtw0kMa4NlSJm1v37E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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