SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de28b649f810dc90c90591363617632118d8285038e73d7bbd9b9be57b5ce776' 
  AND token = 'MGFdmGhhbvozgNTNMrlI4JRyPRKfiqLFxcFWceBCAI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00061

JSON explain

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