SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fed67be1ab3f8a7a4964529dfbe7e7ccd3b7f2521f549df080dedd1fec3b6f33' 
  AND token = 'yy392asJrgmAwhBPVujNHh09i+vakhgcY/SZ7BplzVU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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