SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0fab42cb505214a94b0982e5441ea6b8ad784eae587366b813fa306075dbbe05' 
  AND token = 'RSW6jhbV0bcuu3t4oFV0sQzO0Jq+qiXkTy2PXXfkRtI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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