SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85fd223d7afa0ce4bec2ecae70fe2c91441f2ebe27e4db53f959a52815837535' 
  AND token = '2hopdGGV2QefDuKm8mjqhDn/+7kDWqijtYCed5Li7gs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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