SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6de012b90b470c5bfa1984006729107c783e8c4e8df58a05a3ea6b6bd006af54' 
  AND token = 'sOICeTNovPFXTqcYdyvvNkYkjHKTRewBS4GhsToMVeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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