SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8612ac7701428121572792f2df68faaa16f6046793568535a1cd202e7c73cd60' 
  AND token = 'fSI8+MY+4OL+QbZnmOIHq3rWX/5jUPIsz6JP6BYl13I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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