SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '790a0c1279f37807cb31c1abb2a2c73daad54857141d851a750ab925a107acc2' 
  AND token = 'fYm0qodJdDJ4E/qTDRFQIlwBWSYESC7dzFsW/V46ys4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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