SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c576326c73a54a125c7057b3e24a8bc2653e09f3da9512bf8b177da3bcd97f4' 
  AND token = 'nJRk/sDExE28kXMPZAvrVsS+UrBXqkOR+eKn2XnCU1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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