SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '215d83c686cb1984b87e3d808630cfd8ce17f45642a82a91516371311a1fad7f' 
  AND token = 'smKctVmEzEMx2HBc60oLIywkTWCq2PjQ9FIJYQM+tA0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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