SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b7a1f8ae39b1b51934f1b3f9f109b3be992404710024dd3e2541b7e5db81e0b' 
  AND token = 'UWsLesstcyh2OX81UGlOcl90gFKCxPdt/jla3MGdKGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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