SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4c744d5e7960205fde4290b1471e63042e04098eaed3b44cfda287378440b16' 
  AND token = 'QpmkvkFsjdcuz3ZDeq3PP9WuuLcKFv3b7mXQl2qBgp0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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