SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2267ec413204a8479decff42eb419c9e73e502b378a209ebf20a86501efa2d9' 
  AND token = '+JDzhZmsymwZul7d95VJVnzG7M96C4dl5AUPMp7/qSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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