SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81267cd44df6bc71abbd2a0def82997a7994b81eceb26e78e8109d6550dbe496' 
  AND token = 'MjIWgWKB5tUuTXFtjrhqGwNwyjUFp41DAGf41WzXmgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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