SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b20b2b8f785939c4284e209bbb8d1010ac2e8962579668adcc43c376f16136cb' 
  AND token = 'lNZVV/PMxAjDthvwxrV9jiSFCfndJ57EXWMAQHlgDnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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