SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '348209f12f770940823bfa2e0bf4a2a7f952ab2f61f73cb0ba08d345cd7be1e5' 
  AND token = 'd2tH0a/BLCegCJE49OLhQtW2170phUKLeKeQxW1BPlE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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