SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c109746127bfbd9394f1c3c76001aee6ed20f337236de878168f2e13ee80c3a' 
  AND token = 'uLGlcqVV0I9nHm09shfKmBRZu1hZfLXolAIOJLMus5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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