SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e473e49074beb3676230acfddec35e17af146cc2cc324f5999449d6233e248bb' 
  AND token = '6IRSyvKZGqxFGk3edwPMMneaeAR2iJKIaKmg8sgIspU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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