SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c506250091dec137cf914cf6a80e13502856a975cf7b7a2b7057d69038c87dd' 
  AND token = 'SLLJspFtCJchaFDeTiHKaW884zc5i+Dgpw0729seZjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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