SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '837b4b0a383835f2d243c1355e7b0bd7800408746387757832115a2fddf15db6' 
  AND token = 'tIcF7i1YLEQbKeXDkgbNSLNgFvpZBgDn2BzyLC4jDBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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