SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48affe66d6b57d429123b066674738e296b2ab55a898d1d8ab504c06e8ce3aeb' 
  AND token = 'JsF4EaKNf22bquurkmfOtHH2Ul6kpZO16Iq/0lRgVN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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