SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a740be664e77b17bf6f680fca35b73ab88b6c0dfc3cf6b8269d79953b5b1dcb0' 
  AND token = 'Z8BQaAiOlKL0w8vz5DMCLWb3g/Hh/VJXe2FQaBkZ+t0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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