SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6ba98cb88462cd69684a3bc385feccf74d7bd966db9459e290a0483b2b90157' 
  AND token = '2xqICbAIDaEzi8jScuwYn3CnxGOM0KRv/jcAs0AdKMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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