SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e5d50fe64cdd463e63367518295685f27f8b1a3da12636ca1d0fe46d43622a9' 
  AND token = 'MVbwObQtKzFdYZCHsv8niUQeL0R3ESMr7bpVTjea+n8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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