SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '029961f840a38c503a7a4ac8424c8ce74f4c4f65bf99b74dd6ddbbbc49d4fd42' 
  AND token = 'A/FPowH3pHPXlS6gT6xH6zwcGsGuuwrBRaYnDGjiVcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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