SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51cb121dd9bff04d55118f462c3e0d97f6c305b612cb9c6ea60cfc6a747995ce' 
  AND token = 'yJc82uSIvi0t7oXmR/YDrnHs8duKgfjKqyKZqfzorVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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