SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a56bb880f666722e5280dd7ce7f38d56c22450e385c9561c56ae5f498a923891' 
  AND token = '+PRiQRle59qWFxEGsjccBiYTuOh/sK20uMIrjv/ZfDM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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