SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9cb31710d8e2a661299756584687c62f9da27fdedce27100f46a1f1d22ad9166' 
  AND token = 'oLx/348JJbro6EHkUQTiicaAkfMtk3IvjNvk2GvDKow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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