SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfcc14886318ee021c66b00175260655561c4be3240a0986a1ae74ddbfe840fe' 
  AND token = 'LhdZyJb5srwlohGbcuPLDvVBp1KXpwnJNtGGtCBi+Gg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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