SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15c83966216264d6b6002145d61bbffe42998a74dd623fc7340894bcc494ac75' 
  AND token = 'zBVo0+tAQwFbmAJd3/5fSKmLhm310Whv1GzTG02fcuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00076

JSON explain

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