SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83a23e205eca681b147577be176e29fe241b257ad6866e2a95331e15c754a238' 
  AND token = 'tqjjHVFz0dQquyqJWwIgIRvgOEpuOgxch/r/oIHcxsA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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