SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc3ad0d508ade9a3aad57fd5fc322c00ceb50ca96c03a57a7a3f8caf014fa26b' 
  AND token = 'ZiD6WhPPVi6EzPeTCUpaxcoLnvKWDXCi6v+q9jVU/+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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