SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6a6693455fa063f135cf21b891f89943d7fe3dea82f588fbd83f44ca1026e78' 
  AND token = 'gJojEeUmLCSLw3wTuw/dlBGyz0RbmtAB8YcmuWrql4o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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