SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f0642b281fc74f4e8ed9ff2b9402275cc9fa46a002de66915235fa694b67dcf' 
  AND token = 'cdkhXBYMhImQG8F6NtwcArLaBUGDXzlMRvxTTECz0vg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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