SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76af34ab4b7f36f97f27064d617463d3cd749bd7ca22aa3327208ad0a54cc379' 
  AND token = 'KPS47X4iXsqrZeQ9Mw1Ift3WzPPdF3tWU4mPWcrSUJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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