SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '860cfb858decfedb7a65d2095f183de429aa10721a715cd4979ba64156ac765c' 
  AND token = '0kGYvh5ybb0AHPaGVqqZ4/LSRj+w/CnE+f1hQmXwGhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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