SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '383ce8748818c3a07e8bf8e3b5191207876591f4c473f03e87ed298eabb0f5ea' 
  AND token = 'jOpsVm8nffPgPsMvYtSwEBekjqlkIgYUdnyDJf6m6Q0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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