SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88bc55d0e08bbf3a835836b4f73dce2476c4672b768eec577165b19981aa9e90' 
  AND token = 'CIgCxI86/qg2DoWFSyt6Rjn/8LmYCnoCjjARDaQaMIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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