SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c9b08aca6db9678ded128314575e535c942189c79ba85bbe05e45d66e1bbd78' 
  AND token = '7wSRDjJ+/uxwyPJztTjTpYBtl+W4hxRhUHM3KsK9pxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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