SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5a5ec29a9a967578734b0fe38aa3f58247a4867273f03180594805f1a32faaa' 
  AND token = 'KSix5e6oBVtNABxgXuZjv/0xP5RZx0cMqMBO6Ryrhyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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