SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f4a57ac3151f56711992964c52b5802cee686c47a436c69554e609e353b6ee1' 
  AND token = 'fAJoMN0HEjD/xQOMJLqERnRQvDIzVYHRLvBDsmgkG0o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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