SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ca90a180b42a87292f6aff6a3a1018a51d1a312a8d8c1f291df2411bffcb426' 
  AND token = 'KKxJcFYDLEbcLpN7X43SHA1oPqGKWKHwxO3OCj+yVA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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