SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c8e3c35d710d012c8725d5f97bf00b4f3a1c135f26aa2da8a18cb8e2bc76ce2' 
  AND token = 'DQDxY/fZnKYZOq+uM4h+WJng+uQscJTK3/hy6sCaIKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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