SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9419f50a35e3e444a65896611336a08babab73707e95f7a5b6d24f3cd51b0d9' 
  AND token = 'MT4/BY/Plqf7ED+TNQSlFbV1/6g17zhUDSMVLv2CBlg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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