SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ff3441af7dd9bd4e08ec9b320a8f5846d0f6bcf921480293c0b8d03653d2be9' 
  AND token = 'KbYq5S7x+V1pPgK58/FlWOOkexKgDnWT+JeWpgV/PMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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