SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3541aaaa06f492a383da890976b7f00855225f37067fbd3dbe9c6c3c1a921ae1' 
  AND token = '3IKJtn3uzgb8gSpc0VCjDli9aSB38sHy0tq68/xQ3zs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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