SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21fd3eea9c2df64dc6f5658895c1bd6e73946b4b4c2f19870fd61542d06f2f1a' 
  AND token = 'LKxHIJxoIfFpvg2B0Ae5CWOzhvDSCNuCGJfoZDOhYKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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