SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91c704818c70254221e4fd183bd314e85fa2d32bf213b3f85e8e31a9c4853101' 
  AND token = 'VhN5KqKlARolRUuQxt6m/u2MwkmqBXG6VMogh15aUCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}