SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87d13076c96b50944a772a1cd69fcdfce5641f9edff593e10a431ef9d75dd8d4' 
  AND token = 'FRo2keAlIE3Ecs2O8wM+DGfAFBLY9BHPeiejQANJyx0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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