SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99430bec14e7cbd6811139e83706d2e183d67b36850505c2a0401efe5bee474f' 
  AND token = '9oVMLz0uhygK1BpwOQoTOB4U9P/knxC6YyAnngZKYUs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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