SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fec8079980f757f131ecb0d47725995db246e12f9d00de540603ccad5733a427' 
  AND token = 'Mxg7QOpubZpcJWqX7o2iZkEG/33AJPzxZIHoYzhKn2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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