SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50f04ebe2fb02d169b672531626ca983309c9682c9172355bf4cd68204785969' 
  AND token = 'G9slToOMEg3WE9+VrQzUeXsHmi9f9UViEP2jz24cxH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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