SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4184f59aaff16effa30315c981acd686b09b8f1d431fbdfb631e55270c7f5e3c' 
  AND token = 'JQefM9hf8SuHfRGRSXvD/hCoupUSTtNb/XqDzRB+Xvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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