SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e71987eab2d4ff06764be031ebc4e9a2570ca5b1d87dd6e50b4e6b2cd7f72861' 
  AND token = '8EIWBA4ALcIl+h+NyuxDuC7XVp+RhsWOrG/IJKJvnHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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