SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd1c510d901e56363be92d31cad8576c0abfe728ad06b29821907ed7fc36a351d' 
  AND token = 'uQvdJY7j4Fj5bODHrbCwc9tiLqf7lhb+V/gBO68rY2o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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