SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31fce72828303ceaa9962c3b942d112eed9c94c1a07c6fcbf0244a867630e520' 
  AND token = 'mxi5d3EkJa6DHKLwvWYs3AhaLfSbn3aV+9ELIBgmoA0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}