SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f330d746dbf523b93da6550aeb7912f344bcf618d5e9b3a8a0a74bf84ce4c976' 
  AND token = '+cepGXNEmtVTGSKa4QBRd2JvrO71+Fe2fYRHTYze3jg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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