SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc6003d6cec0e96686cd39108dc9c19736735dc1e3e8b85ad9f301fa1f2f0f66' 
  AND token = 'KHUwA/X/ZZKBQBaFN5nwzwW600b6JE4nwqrUTC0qFTg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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