SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb03cb3e157e44ac810628f3bdd3da447a6f0e8fef3bb77a9675160ae23b3077' 
  AND token = '+SC17a1xxfPmu7RodL9gm0o1kAJLiXbeWRCa33awM9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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