SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c5fbcffe779637388a475ef631cad4a3894ab94d8c893d988822eb34a96c0e9' 
  AND token = '3CSzLliCxt1TfZ7/RmGxyQ66H4slsOwBUjHhaIZXLnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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