SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3572e2b4ccd7cf838b115ee29fea0970bbf19e4b8a3cac27b886b02fed973f9' 
  AND token = '0lDUhNesy7m8o1OdphcbQsElw67Ku6LHl325jJwo56k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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